Proc. Roy. Soc. Ed i n . , Vol. XVI. Plate II. 
Fig. 2. — Vertical section of mucous membrane of the first true digestive (car- 
diac) cavity. In the deeper part the glandular tubes have both principal 
or axial and peripheral cells. Nearer the surface they have only a single 
layer of columnar epithelium, x 15. 
Fig. 1.— Vertical section through the deep layer of the epithelium on the 
surface of one of the finger-like processes from the oesophageal chamber. 
Cubical (a) and polyhedral ( b ) cells well seen, x 200. 
